Foldable Display Device

1. A foldable display device, comprising: a display panel having a first area, a second area, and a foldable area between the first and second areas; a first support plate supporting the first area of the display panel; a second support plate supporting the second area of the display panel; a central support disposed under the foldable area of the display panel, the central support overlapping the foldable area of the display panel in a vertical direction and configured to move in the vertical direction; and a backplate layer supporting the display panel, wherein in an in-folded state, each of the display panel and the backplate layer includes at least one first curved portion having a positive curvature and at least one second curved portion having a negative curvature, wherein the central support includes: a body having a flat top face and supporting the foldable area of the display panel during an unfolding operation; a pair of gears spaced apart from each other and respectively disposed on opposing ends of the body in a length direction of the central support; and a pair of connectors disposed between the body and the pair of gears, wherein each of the pair of gears has teeth formed on each of opposing sides in a width direction of the central support, wherein each of the pair of connectors connects each of the pair of gears to the body, and wherein the body of the central support overlaps the foldable area of the display panel in the vertical direction and extends substantially an entire width of the display panel in the length direction of the central support.

2. The foldable display device of claim 1, wherein the backplate layer includes a patterned portion overlapping the foldable area of the display panel.

3. The foldable display device of claim 1, further comprising at least four rotatable gears under the foldable area of the display panel.

4. The foldable display device of claim 1, further comprising: a first peripheral support slidable while supporting the first support plate; a second peripheral support slidable while supporting the second support plate; and a hinge body disposed under the central support, wherein the central support ascends toward the display panel during the unfolding operation and descends toward the hinge body during an in-folding operation, and wherein the first peripheral support and the second peripheral support move toward the central support during the unfolding operation, and move away from the central support during the in-folding operation.

5. The foldable display device of claim 1, further comprising: a pair of first rotatable gears rotating according to a pivoting motion of a first casing accommodating a first peripheral support, wherein each of the pair of first rotatable gears engages with the teeth of one side of each of the pair of gears of the central support; and a pair of second rotatable gears rotating according to a pivoting motion of a second casing accommodating a second peripheral support, wherein each of the pair of second rotatable gears engages with the teeth of another side of each of the pair of gears of the central support.

6. The foldable display device of claim 5, wherein each of the pair of first rotatable gears is rotatably fitted to a first hinge shaft coupled to the first casing, and wherein each of the pair of second rotatable gears is rotatably fitted to a second hinge shaft connected to the second casing.

7. The foldable display device of claim 6, wherein each of the first hinge shaft and the second hinge shaft extends from a hinge shaft fixing portion received in a hinge body.

8. The foldable display device of claim 4, wherein the hinge body includes: a bottom portion on which the central support is seated during the in-folding operation; a pair of first hinge shaft supports protruding from the bottom portion, wherein a first hinge shaft passes through each of the first hinge shaft supports; and a pair of second hinge shaft supports protruding from the bottom portion, wherein a second hinge shaft passes through each of the second hinge shaft supports, and wherein each of the first hinge shaft supports has a first sector gear, while each of the pair of second hinge shaft supports has a second sector gear.

9. The foldable display device of claim 8, further comprising: a pair of third rotatable gears rotatably coupled to a first casing receiving the first peripheral support, wherein each of the pair of third rotatable gears meshes with the first sector gear of each first hinge shaft support; and a pair of fourth rotatable gears rotatably coupled to a second casing receiving the second peripheral support, wherein each of the pair of fourth rotatable gears meshes with the second sector gear of each second hinge shaft support.

10. The foldable display device of claim 9, further comprising: a pair of first rack gears extending from the first peripheral support and respectively meshing with the pair of third rotatable gears; and a pair of second rack gears extending from the second peripheral support and respectively meshing with the pair of fourth rotatable gears.

11. A foldable display device, comprising: a display panel having a first area, a second area, and a foldable area between the first and second areas; a central support disposed under the foldable area of the display panel, the central support overlapping the foldable area of the display panel in a vertical direction and configured to move in the vertical direction; and a backplate layer supporting the display panel, wherein in an in-folded state, each of the display panel and the backplate layer includes at least one first curved portion having a positive curvature and at least one second curved portion having a negative curvature, wherein the central support includes: a body configured to support the foldable area of the display panel; a pair of gears respectively disposed on opposing ends of the body in a length direction of the central support; and a pair of connectors between the body and the pair of gears, wherein the pair of gears are respectively engaged with a first rotatable gear and a second rotatable gear, wherein each of the pair of connectors connects each of the pair of gears to the body, and wherein the body of the central support has a substantially flat top face, and overlaps the foldable area of the display panel in the vertical direction and extends substantially an entire width of the display panel in the length direction of the central support.

12. The foldable display device of claim 11, further comprising: a first peripheral support slidably disposed on a first side of the central support; a second peripheral support slidably disposed on a second side of the central support opposite to the first side of the central support; and a hinge body disposed under the central support, wherein the central support ascends toward the display panel during an unfolding operation and descends toward the hinge body during an in-folding operation, and wherein the first peripheral support and the second peripheral support move toward the central support during the unfolding operation and move away from the central support during the in-folding operation.

13. The foldable display device of claim 12, wherein the first rotatable gear is fixed to a first casing accommodating the first peripheral support and rotates according to a pivoting motion of the first casing, wherein the second rotatable gear is fixed to a second casing accommodating the second peripheral support and rotates according to a pivoting motion of the second casing, and wherein the central support ascends or descends via the first rotatable gear and the second rotatable gear.

14. The foldable display device of claim 11, further comprising: a first rack gear extending from a first peripheral support toward a hinge body; and a second rack gear extending from a second peripheral support toward the hinge body.

15. The foldable display device of claim 14, further comprising: a third rotatable gear rotatably coupled to a first casing accommodating the first peripheral support and meshing with the first rack gear; and a fourth rotatable gear rotatably coupled to a second casing accommodating the second peripheral support, and meshing with the second rack gear.

16. The foldable display device of claim 15, wherein the hinge body includes: a bottom portion on which the central support is seated during an in-folding operation; a first hinge shaft support protruding from the bottom portion, wherein a first hinge shaft connected to the first casing is fitted into the first hinge shaft support; and a second hinge shaft support protruding from the bottom portion, wherein a second hinge shaft connected to the second casing is fitted into the second hinge shaft support, wherein a first sector gear meshing with the third rotatable gear is disposed on one side of the first hinge shaft support, and wherein a second sector gear meshing with the fourth rotatable gear is disposed on one side of the second hinge shaft support.